5 Replies Latest reply on Feb 18, 2015 3:28 PM by Jared Conway

Flow exiting from a Free Rotor

Hi,

I did simulation on a Free rotor. according to the momentum theory - the flow downstream should be converged to the center. but as you can see in the attached Pic the downstream is diverge.

Is anyone faced with this problem?

thanks

• Re: Flow exiting from a Free Rotor

Does that cut plot represent your entire domain? If that is the entire domain, it seems a little constricted to me. It doesn't look as though you have more than 4 diameter's worth of space downstream.

• Re: Flow exiting from a Free Rotor

I'm not sure about this specific picture but I did it also in domain which was:  In the propeller plane about 35 times larger in every axis, and in upstream and downstreamabout 45.5 times larger in each direction compere to the propeller diameter, and I got same pattern of flow.

• Re: Flow exiting from a Free Rotor

is this a test with a known result?

is this sliding mesh or rotating region?

are there any bc's or is this with just an open environmental condition?

have you followed all recommendations regarding setting up the rotating region?

• Re: Flow exiting from a Free Rotor

Hi,

The magnitude of results (velocity, pressure...) doesn't matter. The problem is that the velocity field doesn't correspond to the theory!!!

the velocity filed by theory (momentum theory) can be viewed on the net under:  "pictures of actuator disc"

(I wrote it also in my discussion about "Free rotor").

It is rotating region enclosed the rotor (averaging) (I tried also Sliding, but there was no major change).

There are no bc's (I think it's not relevant since it deals with external flow).

YES, I did  follow all recommendations regarding setting up the rotating region as far as I know. (I made a real "investigation" about it).

Thank you

• Re: Flow exiting from a Free Rotor

i think best to post an example with a known result so we can dig in and take a look at what is going on

the fact that the problem is solved exactly the same with 2 different methodologies tells me that it is either a setup issue OR an expectation issue